Start-up and Ramp-up of the PLT Tokamak by Lower Hybrid Waves

Start-up and Ramp-up of the PLT Tokamak by Lower Hybrid Waves PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
Lower hybrid waves have been used on the PLT tokamak both to start the plasma current and to ramp it up from pre-existing levels. The waves, at 800 MHz, were launched from a 6-waveguide grill. The phasing between adjacent guides could be selected electronically, and thus the launched spectrum could be set and changed at will. For start-up, the waveguide phase difference was initially set at 0° in order to create a plasma, then switched to 90° to drive the current. Over 100 kA of plasma current, at a density of 0.5 to 1 x 1012 cm−3, was generated in this manner. Ramp-up experiments were performed under a wide variety of conditions. The most efficient ramp-up was found at the lowest plasma densities and with the fastest launched spectrum (n/sub e/ approx. 2 x 1012 cm−3, N/sub parallel/ approx. 1.6 peak); approx. 20% of the launched RF power was converted to (increased) poloidal field energy. All of the ramp-up results are in excellent agreement with a theory which determines the efficiency of ramp-up from the consideration of the relative energy losses of the superthermal current-carrying electrons to collisions and to the opposing inductive E-field.

Start-up and Ramp-up of the PLT Tokamak by Lower Hybrid Waves

Start-up and Ramp-up of the PLT Tokamak by Lower Hybrid Waves PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
Lower hybrid waves have been used on the PLT tokamak both to start the plasma current and to ramp it up from pre-existing levels. The waves, at 800 MHz, were launched from a 6-waveguide grill. The phasing between adjacent guides could be selected electronically, and thus the launched spectrum could be set and changed at will. For start-up, the waveguide phase difference was initially set at 0° in order to create a plasma, then switched to 90° to drive the current. Over 100 kA of plasma current, at a density of 0.5 to 1 x 1012 cm−3, was generated in this manner. Ramp-up experiments were performed under a wide variety of conditions. The most efficient ramp-up was found at the lowest plasma densities and with the fastest launched spectrum (n/sub e/ approx. 2 x 1012 cm−3, N/sub parallel/ approx. 1.6 peak); approx. 20% of the launched RF power was converted to (increased) poloidal field energy. All of the ramp-up results are in excellent agreement with a theory which determines the efficiency of ramp-up from the consideration of the relative energy losses of the superthermal current-carrying electrons to collisions and to the opposing inductive E-field.

Current Ramp-up by Lower Hybrid Waves in the PLT Tokamak

Current Ramp-up by Lower Hybrid Waves in the PLT Tokamak PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
Recent lower hybrid current drive experiments have clearly demonstrated that the current in a tokamak discharge can be maintained by rf drive alone. We have extended the operating regime of such plasma to include ramping-up of the current. We find that at densities of approx. 2 x 1012 cm−3 approximately 25% of the launched rf power is converted to magnetic field energy.

Tokamak Start-Up: Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor (Ettor Majorana International Science Series)

Tokamak Start-Up: Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor (Ettor Majorana International Science Series) PDF Author: Heinz Knoepfel
Publisher: Springer
ISBN: 1475718896
Category : Technology & Engineering
Languages : en
Pages : 425

Get Book Here

Book Description
This book contains the papers presented at the Course on "Tokamak Startup - Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor" which was held in Erice, July 14-20, 1985. The fact that the critical startup and transient phases of a tokamak reactor are now the specific subject of a comprehensive international gathering of fusion specialists seems indicative of the substantial pro gress made in recent years towards attaining controlled ignition of a nuclear fusion fuel, i.e. towards demonstrating the scientific feasibili ty of controlled thermonuclear fusion. In fact, the steady-state burning phase has attracted so far most of the attention of fusion physicists and engineers, as it is conceptually more rewarding, and theoretically easier to handle. However, as for many large engineering systems, - nuclear fis- ... ':1' " . 10 ' ... Entrance to San Rocco's lecturing hall v sion power plants, or aerospace crafts, for example - the major issues of design and operation lie often in the startup, shutdown and power tran sieQt phases, rather than at the full load, or at cruising regimes. In ehoosing the contributions to this 7th Course of Prof. B.

Current Ramp-up with Rf Waves in a Tokamak

Current Ramp-up with Rf Waves in a Tokamak PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
The circuit equations for current-drive in a start-up or ramp-up plasma are derived by finding appropriate response functions in the presence of an electric field. The effect of arbitrary wave-induced fluxes on runaway production and current generation can then be determined. An interpretation of the rather remarkable PLT ramp-up efficiencies, difficult to explain using the steady-state efficiency, is now possible. A parameter regime, available also on reactor-grade devices, is identified wherein quick ramp-up by lower-hybrid waves may be efficient.

Fusion Energy Update

Fusion Energy Update PDF Author:
Publisher:
ISBN:
Category : Controlled fusion
Languages : en
Pages : 100

Get Book Here

Book Description


Energy Research Abstracts

Energy Research Abstracts PDF Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 660

Get Book Here

Book Description


Lower Hybrid Current Drive in the PLT Tokamak

Lower Hybrid Current Drive in the PLT Tokamak PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
Order of magnitude improvements in the level and duration of current driven by lower hybrid waves have been achieved in the PLT tokamak. Steady currents up to 175 kA have been maintained for three seconds and 400 kA for 0.3 sec by the rf power alone. The principal current carrier appears to be a high energy (approx. 100 keV) electron component, concentrated in the central 20 to 40 cm diameter core of the 80 cm PLT discharge.

Government Reports Annual Index

Government Reports Annual Index PDF Author:
Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 872

Get Book Here

Book Description


Electron Heating Using Lower Hybrid Waves in the PLT Tokamak

Electron Heating Using Lower Hybrid Waves in the PLT Tokamak PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 14

Get Book Here

Book Description


Generation of Suprathermal Electrons During Plasma Current Startup by Lower Hybrid Waves in a Tokamak

Generation of Suprathermal Electrons During Plasma Current Startup by Lower Hybrid Waves in a Tokamak PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

Get Book Here

Book Description